In Brazil, Staphylococcus aureus bacteremia (SAB) remains a prevalent and relevant infection, with mortality rates up to 35.1%. This study aims to evaluate mortality in methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia and associated risk factors. Retrospective, single-center cohort study conducted in a tertiary hospital between January 2014 and December 2023, including patients ≥18 years with at least one positive blood culture for MSSA. Demographic, clinical, microbiological and therapeutic variables and their relationship with mortality were analyzed. A total of 121 episodes of SAB were included, with 7-day mortality of 15.7% and 30-day mortality of 35.5%, consistent with the literature. Hospital-acquired origin (OR = 3.19; p=0.003) and pneumonia as the primary focus (OR = 5.6; p=0.006) were associated with mortality, in line with previous studies, as was complicated bacteremia (OR = 21.4; p=0.035), reinforcing the relationship between persistent infection, septic emboli, endocarditis and worse outcomes. The Pitt Score was significantly higher among deaths (p<0.001) and was the only independent predictor of mortality in multivariate analysis (OR = 1.349; p<0.001). High resistance to erythromycin (50.4%) and clindamycin (42.1%) was observed, with low resistance to other classes. Lack of follow-up blood cultures and echocardiography was more common among deaths within 7 days (p<0.001), which may reflect greater initial severity or the need for early investigation. Infectious diseases consultation had a protective effect in univariate analysis (OR = 0.46; p=0.045), reinforcing studies that show specialized follow-up reduces mortality, with impact from the episode up to five years later. Unlike the literature, there was no association between mortality and age, sex, comorbidities, time to blood culture positivity or adequacy of empirical therapy, suggesting that initial clinical severity and complications may have greater impact on outcomes. MSSA bacteremia is a severe infection with high mortality, particularly when associated with pneumonia, hospital-acquired origin, complications and high severity scores. The Pitt Score proved to be the main prognostic tool. Strategies such as early infectious diseases consultation, assessment of complications and risk stratification should be reinforced to improve outcomes.
Ferrari et al. (Sun,) studied this question.